Method for treating coiled bodies



Aug. 30,1949. E. A. NoRDBl-:RG

METHOD FOR TREATING COILED BODIES Filed July l1, 1945 is initiated. While the ,strips may be assembled with varying numbers of layers or plies, and in various successive arrangements appropriate to the particular type of wound body which is desired, I have chosen to illustrate for explanatory purposes a typical assembly of six strips IZ-I'I. The strips I3 and I6 are composed of conductive material such as foil. Each of these strips is sandwiched between a pair of dielectric strips composed of paper or the like, the foil strip I3 being sandwiched between the paper layers I2 and I4, and the foil strip I6 being sandwiched between the paper layers l and I'l. In initially bringing this group of layers into superposed relationship, the strips are laid one upon the other so that the paper or non-conductive layers project beyond the ends of the foil or conductive layers. This is to assure a condition of electrical insulation between the conductive strips I3 and I6 at the core of the ultimate wound body. After the strips have been brought into desired superposed relationship, they are threaded into engagement with the arbor. In the case of a split mandrel of the character shown. this involves the insertion of the strips into and through the space between the two portions I9 and I I. The arbor or mandrel is then rotated in the direction of the arrow I9, and this initiates a winding of the strips into a coiled body 2 I. After the desired lengths ci strips have been wound, they are cut off at their outer ends in a manner which is not illustrated in the present drawings, with the paper layers having their ends projecting beyond the outer ends of the foil layers, thus electrically shielding the outer ends of the foil layers from each other. The wound body is then removed from the arbor. In the case of a split mandrel of the character shown, this procedure is facilitated by the longitudinal withdrawal of one of the mandrel sections I0, I l, prior to the similar withdrawal of the other.

The substantially cylindrical body which is thus produced has one or more gaps or spaces in its axial region. For the sake of convenience, these gaps have been shown in Figure 1 as a single axial opening I9, and may be designated collectively as a hole.

In ordinary commercial practice, a sticker or label is immediately applied to the peripheral surface of the wound body so as to retain the strips in wound condition, and the body is then subjected to the usual heat and vacuum and impregnation treatments. Prior to or during these procedures, it may be flattened by a slight pressure, thus squeezing the body into a compacted shape of substantially elliptical cross-section, or the initial substantally cylindrical shape may be retained.

In accordance with my present invention, however, the wound body 2|, as it is removed from the winding arbor, is not yet ready for the application of the conventional sticker or label, and is introduced, as indicated by the arrow 2G, into a suitable apparatus by means of which the present special treatment is performed.

There are winding arbors in common usage which are slightly different from the split mandrel construction shown in Figure 3, but in each case, the presence of the arbor or its component parts always results in the provision of an axial hole as indicated at I9 in Figure 1. It will therefore be understood that the diagrammatic showing of Figure 3 is purely illustrative to explain the presence of the hole I9 in the wound body ZI, and that the invention is applicable to any arborwound body which is characterized by the fact that it is substantially cylindrical, that it has an axial space or hole I9, and that it is composed of spirally-wound strips, the outer ends of which are illustratively shown at the 1eft of Figure 1 and designated by the reference numeral 22.

The method steps of the present invention may be carried out in a variety of ways, and the apparatus shown in Figures 1 and 2 is merely an illustrative preferred structure which has proven satisfactory for the present purpose. It consists of two continuous belts 23 and 24. The belt 23 extends around the pulleys 25 and 2E, while the belt 24 extends around similar pulleys 2l and 28, these pulleys being so arranged that each belt has a span arranged substantially in a plane, these spans being juxtaposed in spaced substantially parallel relationship. By means of a suitable mechanism, such as that which is shown in Figure 2, the span portion of the belt 23 is caused to move longitudinally in the direction of the arrow 29, while the opposed span portion of the belt 24 is caused to be moved in the opposite direction as shown by the arrow 30. The belt 23, however, is caused to have a lineal speed greater than that of the belt 24. Each of the belts has an outer portion formed of relatively soft and yieldable yet resilient material, such as rubber or the like. I have illustratively shown each belt formed of a backing 3i (see Figure 2) of canvas or the like, and an outer operative portion 32 of resilient material of the character mentioned.

Associated with the belt 23, between the pulleys 25 and 26, is a rigid panel 33 over which the operative span of the belt travels. A similar rigid panel 3d is mounted between the pulleys 2l and 28 to serve as a backing over which the operative span of the belt 24 travels. The panels 33 and 34 may be mounted on a convenient supporting structure 35 (Figure 2) which supports at least one pair of the belt pulleys, as well as the driving mechanism.

Before describing the operation of the apparatus and the features lof the present method and procedure, attention is directed to Figure 2 in which I have shown one illustrative way of driving the belts 23 and 24 in the desired relationship. The pulley 25 may be mounted, for example, on a shaft 35 which is journaled in the supporting structure 35 and which carries a pinion or gear 3l. An intermediate pinion l0 may be mounted on a jack shaft AI. The shaft 38 may serve as the driving shaft, connected (in a manner not shown) to a suitable source of power such as an electric motor or the like. The interconnection of the gears 39, 49 and 3l, brings about a rotation of both pulleys 25 and 2? when the driving shaft 38 is rotated. Where this driving mechanism is associated with the pulleys 2E and 2l as indicated for illustrative purposes, the other pulleys 2S and 28 (at the right of Figure 1) may be mounted in any convenient manner to serve merely as idler or guiding pulleysl By making the gear 37 slightly smaller in diameter than the gear 39, the lineal speed of the belt 23 may be caused to be slightly greater than that of the belt 215, as hereinbefore mentioned.

Reverting now to the arbor-wound coiled body 2i; this body is introduced at the region 29 to the action of the cooperating belts 23 and 2li. It is introduced in the relationship shown in Figure l, its axis being transverse with respect to the operative portion of the belts, and the free ends of the strips of which it is composed being arranged as shown at 22 in Figure 1. The greater lineal speed of the belt 23 causes this body to be immediately engaged by the two belts, in an interposed relationship between the operative span portions of the belts. As a result, the body advances slowly and presently assumes a position such as that indicated by the reference numeral 42. Ultimately, the body advances completely through the apparatus to a discharge point as indicated by the arrow 43. Intermediate positions of the body are illustratively shown at 44 and 45.

As will be observed, the outer portions of the two belts serve as pressure surfaces adapted frictionally to engage the body 2| on its peripheral surface, the regions of engagement being substantially diametrically opposed. The yieldable resilient nature of these pressure surfaces causes them to engage the coiled body frictionally, and to impart tangential forces to the body, as well as an inwardly-radial pressure. The tangential forces impart a twirl to the body in the direction which winds the body more tightly about its axis. At the same time, the continuous radial pressure induces the body gradually to reduce its volume. The result is indicated by comparing the bodies designated by the reference numerals 42, 44 and 45. When the body is introduced to the action of the belts or pressure surfaces, it has a relatively large initial external diameter. As it twirls on its axis, under the inuence of the frictional force applied by the pressure surfaces, and as these pressure surfaces continuously exert an inwardly-radial pressure upon it, this external diameter gradually decreases, and at the same time, the hole I9 gradually diminishes in size until the body ultimately leaves the lapparatus in a relatively compacted condition. In this condition, it is still substantially cylindrical in shape, the strips of which it is composed are still in the desired relationships to one another, yet the arbor hole I9 has been completely eliminated. The body is therefore substantially rigid and compact, and after a sticker or the like has been applied to its outer surface, to hold the outer ends of the strips in position, the body lends itself readily to further handling and treatment, without any danger of maladjustment of the component strips.

Bodies .may be subjected to the action of the apparatus in a continuous and successive manner, and the showing of Figure 1 might be construed, if desired, to represent four separate coiled bodies under simultaneous treatment. That is, the reference numeral 45 might be construed as designating a body which is just ready to leave the apparatus in compacted condition, the reference numerals 42 and 44 might be deemed to designate two other bodies which are in process of being treated, and the reference numeral 2| may be deemed to represent a body at the instant of its introduction to the action of the apparatus.

Obviously, bodies of any size may be treated, it being understood that the spacing of the operative portions of the belts will always be adjusted to accommodate a predetermined range of sizes. The operative spans of the belts may be of any desired longitudinal extent, and the lineal speeds at which the belts travel .may be adjusted to suit varying requirements.

Under certain circumstances, the two opposed pressure surfaces may be constructed otherwise than as portions of two belts. For example, one of the pressure surfaces might be a stationary element While the other pressure surface travels. To conserve space. however, it is preferable that 6 both belts be caused to move, with one belt having a slightly greater lineal speed. This results in subjecting the wound body to the twirling and pressure action of the pressure surfaces for a maximum period of time within a minimum amount of space.

The tightly-wound bodies resulting from the present treatment are particularly well adapted to form condenser devices or the like in which the body is embedded or molded within an enclosure of plastic or the like. In fact, the compacted body is in an admirable structural state for handling and mounting in any convenient or desired type of ultimate enclosure. Its compact and rigid nature minimizes the likelihood of undesirable shifting of the foil and paper strips at the core of the body, as a result of which there is a minimum of loss during the manufacturing process, due to defectively-wound bodies, and a minimum likelihood that the completed capacitors or equivalent devices will prematurely break down electrically.

Having thus described my invention and illustrated its use, what I claim as new and desire to secure by Letters Patent is:

1. The method of treating a coiled arborwound condenser body, which consists in twirling the body on its axis and simultaneously exerting a continuous inwardly-radial pressure upon its peripheral surface, said twirl being in the direction which coils the body more tightly about its axis.

2. The method of treating a coiled arbor- Wound condenser body, which consists in twirling the body on its axis and simultaneously exerting a continuous inwardly-radial pressure upon its peripheral surface, said twirl being in the direction which coils the body more tightly about its axis, and said pressure being exerted from points in substantially diametric opposition to each other.

3. The method of making a tightly-wound coiled condenser body composed of alternate conductive and dielectric layers, which consists in winding a series of conductive and dielectric strips in appropriate superposed relation upon an arbor, removing the wound body from the arbor, and then twirling the body on its axis and simultaneously exerting a continuous inwardly-radial pressure upon its peripheral surface, said twirl being in the direction which coils the body more tightly about its axis.

4. In the art of mak-ing an electrostatic condenser of the character described, the procedure which consists in frictionally engaging the peripheral surface of a spirally-coiled body at substantially diametrically opposite regions, and subjecting said body at said regions to oppositelydirected tangential forces and to an inwardlyradial pressure, said tangential forces being applied in directions Which impart to the body a volume-reducing twirl which coils the body more tightly about its axis.

ERNST A. NORDBERG.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 43,735 Chase Aug. 2, 1864 '777,335 Dietz Dec. 13, 1904 2,358,654 Nordberg Sept. 19, 1944 2,360,275 Rau Oct. 10, 1944 

